Over the past thirteen years the germfree laboratory at Louisiana State University School of Medicine has played a leading role in the development of germfree dogs as a biomedical research tool. The purpose of this project is to establish a major research effort, with gnotobiotic dogs and rodents, on the effects of the microbial flora in normal physiology and in specific gastrointestinal diseases. One major objective is to gain a better understanding of the complex interrelationships between the intestinal microorganisms and the ability of the host to absorb vitamine B-12 and fats. Surgical blind-loops will be produced in gnotobiotic animals and the effects of specific microorganisms from conventional rats suffering from the blind-loop syfdrome on vitamin B-12 absorption and steatorrhea will be studied. In this manner the microbial pathology of these syndromes will be studied in experimental animals under controlled conditions. Rigorous physiological, microbiological and anatomical experimentation will be conducted. Studies of normal gastrointestinal function in germfree animals have a practical value for patients receiving massive antibiotic therapy and for patients maintained in controlled microbial environments, i.e. leukemia patients, transplant patients and immunologically deficient infants. The completion of the proposed project will provide the clinician with the fundamental scientific data necessary to improve the prophylaxis and therapy of disease due to an altered intestinal flora.